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Landlord Mortgage Stress Test

Last Updated: 15 June 2026

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Mortgage stress test calculator

Enter your current deal and three rate scenarios — see payment shock, cash flow impact, and buffer requirements.

Current mortgage
£
%
mo
%
Auto-reversion rate if you do nothing
Income & costs
£
£
Agent, maintenance, insurance, voids (excl. mortgage)
New rate scenarios
%
%
%
New deal terms
SVR trap — cost of doing nothing at expiry
ScenarioMonthly paymentCash flow/moBreak-even rentSurplus/shortfallPositive?
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Why landlords need to stress test their mortgages

Hundreds of thousands of UK landlords locked in BTL fixed rates at 2–3% during 2020–2022. Those deals are rolling off now — and replacement rates are 4–6%+. For a landlord with a £200,000 interest-only mortgage, that is a jump from approximately £400/month to £850–£1,000/month. Whether rental income can absorb that shock determines whether the property remains viable or becomes a monthly liability.

The SVR trap

When a BTL fixed rate expires, the mortgage reverts automatically to the lender's Standard Variable Rate — currently averaging around 7.5–8.5% for BTL products. Acting 3–6 months before expiry is all that's required to avoid it. Most lenders allow you to lock in a new rate up to 6 months ahead, with the option to re-apply at a lower rate if rates fall before your deal starts.

Frequently asked questions

What happens to my BTL mortgage when the fixed rate ends?
Your mortgage reverts automatically to the lender's Standard Variable Rate. For BTL products, SVRs currently average around 7.5–8.5% — significantly above competitive new fixed rate products. To avoid the SVR, remortgage before expiry or arrange a product transfer with your current lender up to 6 months in advance.
Should I fix for 2 or 5 years at remortgage?
Two-year fixes typically offer slightly lower rates but more frequent remortgage decisions. Five-year fixes cost slightly more but lock in certainty longer. For landlords with thin margins where any rate rise would turn the property negative, a five-year fix provides more protection. Use the break-even table above — if you can afford the worst-case rate comfortably, a shorter fix preserves flexibility.
How much cash buffer should a landlord hold?
At minimum, 3–6 months of mortgage payments per property. For properties with thin margins (under £100/month cash flow), hold 6 months. Add 1 month's rent per property as void cover. The buffer calculator above shows the exact amount needed to cover any shortfall at each rate scenario.
Can I switch from repayment to interest-only at remortgage?
It is possible but harder than before — you must demonstrate a credible repayment strategy (property sale, investments, or other assets) and pass the ICR test at the new IO payment. The benefit is a lower monthly payment improving cash flow; the cost is that you stop building equity through capital repayment.

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DisclaimerEstimates for planning only. Actual SVR rates, lender criteria, and product availability vary. Always speak to a qualified, FCA-regulated mortgage broker before making any remortgage decision.

About the author

Kelvin Peltier

Retail leader, entrepreneur and founder of Poqet.io.

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✓ Editorially reviewed — all Poqet guides are checked for factual accuracy before publication and updated when UK rates or legislation change. Editorial Policy